Introduction to Yeast Media

Introduction

Figure 1. A Typical Yeast Cell

Yeasts are eukaryotic microorganisms whose genomes have been comprehensively studied and some have been sequenced. They are relatively easy to grow under laboratory conditions. Moreover, despite their small genome size, they display cellular features and processes that are highly conserved amongst most eukaryotes. For instance, they have membrane-bound organelles, cytoskeleton, nuclear DNA, and transcription mechanisms that are similar to those found in higher eukaryotes. Furthermore, yeasts have many well-characterized secretory proteins and pheromones. Several yeast genes involved in protease processing and secretion have also been identified. Thus, yeasts can be used for several eukaryotic gene and protein studies with the aid of suitable molecular biology tools. Some applications for yeast cultures include synthesis of protein expression systems, the study of specific gene or protein functions, and the analyses of novel protein interactions. They are also used for many industrial applications such as fermentation, baking, and bioremediation.

Yeast culture media play a significant role in supporting growth in both small and large scale purposes. Typically, a yeast culture medium includes peptone, yeast extract, and dextrose or glucose. Even slight differences in media composition can yield yeasts with distinct growth characteristics.

Types of Yeast Media

Figure 2. Classification of Complex Yeast Growth Media

Figure 3. Classification of Synthetic Yeast Growth Media

The minimal synthetic media can be used with drop-out medium supplements to create selective media for growing auxotrophic yeast cultures.

Furthermore, yeast strains can be sporulated using specific sporulation media. Indicator media can also be used to distinguish yeast strains that either ferment or do not ferment specific sugars, such as galactose or maltose.

Yeast Media Options

We offer a broad range of high-quality yeast culture media to suit your unique research needs. They are listed as follows:

1. YPD medium
A nutritious medium available in liquid (broth) or solid (agar) forms for the growth and propagation of yeast cultures. It primarily contains of bacteriological peptone, yeast extract, and glucose. This medium is non-selective for Candida, Pichia, Saccharomyces, and Zygosaccharomyces.

2. Yeast Synthetic Drop-out Medium Supplements
The selection of plasmids in yeast is usually based on the use of auxotrophic mutant strains, which cannot grow without a specific medium component (like an amino acid, purine, or pyrimidine). Transformation with a plasmid containing the mutated gene enables the transformant to grow on a medium lacking the required component. Thus, drop-out medium supplements can be used to select transformed yeast cultures.
Please refer to the selection guide below for further details.

3. Yeast Nitrogen Base (YNB with or without amino acids)
Yeast Nitrogen Base is a highly-referenced growth medium used for the cultivation of yeast. This nutrient-rich microbial medium contains nitrogen, vitamins, trace elements, and salts. It is suitable for use in classifying yeasts based on amino acid and carbon requirements. With an added carbon source, YNB with amino acids can be used for susceptibility testing of fungi.

4. EnPresso^TM Y Defined Growth System is a proprietary formulation of buffering salts, amino acids, carbon source and polysaccharides. The formulation is designed to yield at least 2x more protein compared to traditional culture media.

Yeast Culture Media Selection Guide

Table 1. YPD & YNB Media

Product Number	Name	Description	Media Components	Selectivity	Reconstitution
Y1375	YPD Broth	liquid growth medium for yeast	20g/L peptone 10g/L yeast extract 20g/L glucose	non-selective for Candida, Pichia, Saccharomyces & Zygosaccharomyces	-Suspend 50g in 1L of distilled water -Autoclave for 15 minutes at 121 °C
Y1500	YPD Agar	solid growth medium for yeast	20g/L peptone 10g/L yeast extract 20g/L glucose 15g/L agar	non-selective for Candida, Pichia, Saccharomyces & Zygosaccharomyces	-Suspend 65g in 1L of distilled water -Heat to boiling while stirring to dissolve all ingredients completely -Autoclave for 15 minutes at 121 °C
Y0626	Yeast Nitrogen Base Without Amino Acids	highly-referenced growth medium yeast	consists of nitrogen source, vitamins, trace elements and salts	non-selective for Candida, Pichia, Saccharomyces & Zygosaccharomyces	-Make a 10x concentrated stock solution by stirring to suspend 6.8g yeast nitrogen base powder, 5g glucose, and 5-10mg of appropriate amino acid in 100mL water -Warm if necessary to aid solubilisation -Filter sterilize and store at 2-8 °C. -Dilute the 10x concentrated stock to a 1x working solution by adding 100mL concentrated stock to 900mL sterile water
Y1250	Yeast Nitrogen Base With Amino Acids	non-selective, highly-referenced growth medium for yeast	consists of nitrogen source, vitamins, amino acids, trace elements and salts	non-selective for Candida, Pichia, Saccharomyces, and Zygosaccharomyces	-Make a 10x concentrated stock solution by stirring to suspend 6.7g yeast nitrogen base powder and 5g glucose in 100mL water -Warm if necessary to aid solubilization -Filter sterilize and store at 2-8 °C -Dilute the 10x concentrated stock to a 1x working solution by adding 100mL concentrated stock to 900mL sterile water
Y22001	EnPresso Y Defined	defined growth media	proprietary formulation of buffering salts, amino acids, carbon and polysaccharides	non-selective for Pichia & Saccharomyces	Suspend tablet in water and shake to dissolve

Table 2. Synthetic Drop-Out Medium Supplements
Note: The following mixtures of amino acids and other nutrients need to be added to Yeast Nitrogen Base Without Amino Acids (Catalog Number Y0626).

Product Number	Missing Supplements	Amino Acids	Other Nutrients
Y1501	Uracil	All standard amino acids are present at a concentration of 76mg/L except for leucine, which is present at 380mg/L.	Adenine (18mg/L), inositol (7 mg/L), p-aminobenzoic acid (8mg/L)
Y1751	Histidine	All standard amino acids except for histidine. All the amino acids are present at a concentration of 76mg/L except for leucine, which is present at 380mg/L.	Adenine (18mg/L), inositol (76mg/L), uracil (76mg/L), p-aminobenzoic acid (8mg/L)
Y1896	Lysine	All standard amino acids except for lysine. All the amino acids are present at a concentration of 76mg/L except for leucine, which is present at 380mg/L.	Adenine (18mg/L), inositol (76mg/L), uracil (76mg/L), p-aminobenzoic acid (8mg/L)
Y1376	Leucine	All standard amino acids except for leucine. All the amino acids are present at a concentration of 76mg/L.	Adenine (18mg/L), inositol (76mg/L), p-aminobenzoic acid (8mg/L), uracil (76mg/L)
Y1876	Tryptophan	All standard amino acids except for tryptophan. All the amino acids are present at a concentration of 76mg/L except for leucine, which is present at a concentration of 380mg/L.	Adenine (18mg/L), inositol (76mg/L), p-aminobenzoic acid (8mg/L), uracil (76mg/L)
Y0750	Leucine and Tryptophan	All standard amino acids except for leucine and tryptophan. All the amino acids are present at a concentration of 76mg/L	Adenine (18mg/L), inositol (76mg/L), p-aminobenzoic acid (8mg/L), uracil (76mg/L)
Y1771	Uracil, Leucine and Tryptophan	All other standard amino acids except for leucine and tryptophan. All the amino acids are present at a concentration of 76mg/L	Adenine (18mg/L), inositol (76mg/L), p-aminobenzoic acid (8mg/L)
Y2146	Histidine, Leucine, and Tryptophan	All standard amino acids except for histidine, leucine and tryptophan. All the amino acids are present at a concentration of 76mg/L.	Adenine (18mg/L), inositol (76mg/L), p-aminobenzoic acid (8mg/L), uracil (76mg/L)
Y2021	Histidine, Leucine, Tryptophan, and Adenine	All standard amino acids except for histidine, leucine and tryptophan. All the amino acids are present at a concentration of 76mg/L.	Inositol (76mg/L), p-aminobenzoic acid (8mg/L), uracil (76mg/L).
Y2001	Histidine, Leucine, Tryptophan, and Uracil	All standard amino acids, except for histidine, leucine and tryptophan, are present at a concentration of 76mg/L.	Adenine (18mg/L), inositol (76mg/L), p-aminobenzoic acid (8mg/L).

Table 3. Other Supplements for Yeast Cultures

Product Number	Name	Description	Application	Features & Benefits
T2559	EZMix™ Tryptone	Peptone derived from the enzymatic digest of casein; rich in tryptophan; also contains a mixture of nitrogen, amino acids, & vitamins	Often used in culture media	Tryptone EZMix powder provides: - Granulated, dust-free format for safer handling and faster mixing - Easy scale-up using larger package sizes
G5516	Glycerol	Viscous liquid widely used in molecular biology research	used for storage of microbial stocks	The product is Molecular Biology grade and is suitable for molecular biology applications

Synthetic Media Growth Test Results

+ = growth observed; – = no growth observed

Synthetic medium Relevant genotype	Y1501 without uracil	Y1751 without histidine	Y1896: without lysine	Y1376: without leucine	Y1876: without tryptophan	Y0750: without Leu & Trp	Y1771: without Ura, Leu, Trp	Y2146: without His. Leu. & Trp	Y2021: without His, Leu, Trp, & Trp	Y2001: without His, Leu, Trp, & Ura	YPD
ade2, lys2, trp1, his3, ura3, leu2 [pCEN HIS3]	-	+	-	-	-	-	-	-	-	-	+
ade2, lys2, trp1, his3, ura3, leu2 [pCEN TRP1]	-	-	-	-	+	-	-	-	-	-	+
ade2, lys2, trp1, his3, ura3, leu2 [pCEN LEU2]	-	-	-	+	-	-	-	-	-	-	+
ade2, lys2, trp1, his3, ura3, leu2 [pCEN URA3]	+	-	-	-	-	-	-	-	-	-	+
ade2, lys2, trp1, his3, ura3, leu2 [pCEN LEU2, pCEN TRP1]	-	-	-	+	+	+	-	-	-	-	+
ade2, lys2, trp1, his3, ura3, leu2 [pCEN LEU2, pCEN TRP1, pCEN HIS3]	-	+	-	+	+	+	-	+	-	-	+
ade2, lys2, trp1, his3, ura3, leu2 [pCEN LEU2, pCEN TRP1, pCEN URA3]	+	-	-	+	+	+	+	-	-	-	+
leu2, trp1, ura3-52	-	+		-	-	-	-	-	-	-	+
lys1	+	+	+ -	+	+	+	+	+	+	+	+

References

1. Atlas RM, Atlas RM. Handbook of Microbiological Media. https://doi.org/10.1201/9781420039726

2. Sherman F. 2002. Getting started with yeast.3-41. https://doi.org/10.1016/s0076-6879(02)50954-x

3. Kaiser C, Michaelis S, Mitchel A. Methods in Yeast Genetics, a Cold Spring Harbor Laboratory Manual (Cold Spring Harbor, NY: 1994)..